View Full Version : Re: M50 Won't start
Well some of you might remember me finding out the problem so bare with me if you remember.
I have a 1991 525i and the engine would flood itself out every time I would crank it. When you remove the fuel pump fuse it will start up and rev until 3k rpm. So I checked fuel pump relay, fuel pump wiring, Fuel pump, and the Fuel pressure regulator (FPR). No work. Then I switched out the injectors. Still no work. Then I finely burrowed someone’s ecu and it started and I drove it for about 20 minutes w/ out problem so I took that out and returned it. (That run was on a known working set of injectors)(From my e32). While waiting for the new computer to arrive I switched the injectors back to the original ones. So hers the bad f*ckin news. Got new ecu online plugged it in ran like a beauty, drove to get gas, then got taco bell, got back in car started it and got back on the road home. While slowing down to stop at a light all of the engine lights went on and I started to laugh then I realized it was something serious and the engine had stopped running. So I quickly shift into park and crank and I get the dreaded smell of a flooded engine. Same frigin problem all over again the car fry’s this brand new computer in the same way it messed up the old one. Same exact symptoms. So now back to square one -200$ and a broken glass that I threw out of anger.
Need help ASAP so thanks in advance guys.
Now I have narrowed it down to something on the car is making the car eat ECU's this is its 3rd one. The second was a rebuilt version of the first one.
I went and checked the resistnace of the injectors and all of them were between 15.7 and 15.9 ohms
and none of them are grounded but one of the pins on the ecu connector has continuty with +12v
im gonna go back out and verify
nm i made a error no +12 v to the injectors. now im realy stumped...
Well I think my testing process is flawed. How should I go about testing the engine wiring harness? I have a digital multimeter and it beeps when you touch the leads together. People say oh check for shorts. Well im unsure on the process to do that.
Javier
07-07-2005, 04:39 PM
to the injectors connector (one by one). You should see pulsating light, if permanent on, the output drivers from the ECU are gone, if any one of them is permanently off, its wires may be shortcircuited.
Use an interior light bulb or similar to limit the current to the very minimum, you don't need much to test. If you have one of those led probes, (available at Pepboys) it should do it.
Javier
Ok ill test that tomrow and like you said in your email how do i test if i have weak spark? Also how do i test the ignitiion coils? i did the test that the bently manual says and they are all with in range of how many ohms they stated they should be.
By the way thanks for all of your help unlike the people at bimmerfourms makeing fun of me for not being able to figure this out. Iv asked 2 bmw dealerships and 3 shops and all of them are baffled and i don't have the money to have them look at it for 6 hrs at 110 a hr.
Javier
07-08-2005, 05:51 AM
connector pin 4a and the sparkplug connection in the coilpack, it is the high voltage coil, compare readings between coils (have no values to offer you). Also can wire a light bulb between terminals 1 and 15 of the coil connector. You should have a flashing light wile cranking. This will test DME transistor (six in total), as we already know that whatever you have in there is taking out the DME. (Remember coil and injector feeders are not fused, attention to ground shortcircuits).
I feel the problem is more toward the injectors, let us know what the injector operation test turned out to be (Permanently energized?).
Javier
Bellicose Right Winger
07-08-2005, 11:35 AM
I can't believe all those DME's are fried. Can you test them in the vehicle that gave you the loaner DME? If indeed they're bad, you need to discover cause before any more get ruined. It could be a wiring issue that comes and goes when you plug/unplug the DME or jostle other wires.
Paul Shovestul
Well some of you might remember me finding out the problem so bare with me if you remember.
I have a 1991 525i and the engine would flood itself out every time I would crank it. When you remove the fuel pump fuse it will start up and rev until 3k rpm. So I checked fuel pump relay, fuel pump wiring, Fuel pump, and the Fuel pressure regulator (FPR). No work. Then I switched out the injectors. Still no work. Then I finely burrowed someone’s ecu and it started and I drove it for about 20 minutes w/ out problem so I took that out and returned it. (That run was on a known working set of injectors)(From my e32). While waiting for the new computer to arrive I switched the injectors back to the original ones. So hers the bad f*ckin news. Got new ecu online plugged it in ran like a beauty, drove to get gas, then got taco bell, got back in car started it and got back on the road home. While slowing down to stop at a light all of the engine lights went on and I started to laugh then I realized it was something serious and the engine had stopped running. So I quickly shift into park and crank and I get the dreaded smell of a flooded engine. Same frigin problem all over again the car fry’s this brand new computer in the same way it messed up the old one. Same exact symptoms. So now back to square one -200$ and a broken glass that I threw out of anger.
Need help ASAP so thanks in advance guys.
Now I have narrowed it down to something on the car is making the car eat ECU's this is its 3rd one. The second was a rebuilt version of the first one.
Hypr5
07-08-2005, 11:54 AM
Ok - I've been helping him with this project and trust me - it's a headache.
The DMEs are in-fact fried. No, we didn't test them on other vehicles, but anytime we plug a new ECU in, it works. (For how long.. nobody knows)
I DO think it's either coils, injectors or wiring SOMEWHERE, but I don't think it has to do with wire movement as this last ECU died while we were at a stop. It's frustrating.
The fact that the loaner ECU didn't die and it drove the car for longer than this ECU tells me that it may be injectors (because at the time, there were known working injectors from another vehicle installed).
Whats the likelyhood of injectors causing this sort of problem? Has it been heard of before?
Bellicose Right Winger
07-08-2005, 01:00 PM
Lets work backwards from here. What was rebuilt on this DME?
Paul Shovestul
.....The second was a rebuilt version of the first one.
If I checked the resistnace of the injectors and all of them were between 15.7 and 15.9 ohms, could there be a problem of them killing the ecu or should i use a ammeter to see how much current draw there is? How do i test the coilpacks the right way because i was reading and the way bently says to do it isn't 100% right.
Bellicose Right Winger
07-08-2005, 01:21 PM
We share your frustration as many of us have wrestled with similar problems.
Interesting perspective. The fact that the loaner DME didn't die, is precisely what causes me suspect the claim that "they're all fried".
DME's die when the switching transistor that completes the path to ground for the injector or the ignition coil is asked to conduct more current then it's designed to. So when a coil shorts internally, it's resistance drops and it draws more current, overloading the switching transistor in the DME. Likewise a wiring problem that puts 12 volts directly to the switching transistor rather then first thru the injector or ignition coil, would also fry the DME. Need to find out what was changed when previous DME was repaired/rebuilt.
If indeed DME's are bad, sounds like classic case of bad ignition coils.
I suggested in a post made long ago that taking coils to a TV repair shop and having them tested on a device called a 'ringer' might be worth a try.
Paul Shovestul
Ok - ........The fact that the loaner ECU didn't die and it drove the car for longer than this ECU tells me that it may be injectors (because at the time, there were known working injectors from another vehicle installed).
Whats the likelyhood of injectors causing this sort of problem? Has it been heard of before?
OH ONE MORE THING I FORGOT TO MENTION!!! When we were driving there was no trans program but when we had the old (suspected fry'd ECU) in the car we had a trans prog, then when we put the known working ecu in and were driving (before it died) there was no trans program, the seccond the car died trans program came back on. is there a chance that the transprogram is eating the ecu? and is there somehting i overlooked like a diferent way to reset the ecu or anything?
do you know a link that talks about the ignition coils, or a little more info about the "ringer" test? or a link to that thread? thanks
-karl
Bellicose Right Winger
07-08-2005, 02:50 PM
Due to risk of ruining another DME, most shops replace all the coils.
http://www.bimmer.info/forum/showthread.php?t=2707&highlight=shovestul+ringer
http://groups-beta.google.com/groups?hl=en&lr=&safe=off&num=100&q=ringer+%28fbt+OR+lopt+OR+coil%29+group%3Asci.ele ctronics.repair&safe=off&qt_s=Search
A ringer will detect coils that have shorted windings that won't show up with a resistance test.
Compounding the problem, it seems you're dealing with a problem that only shows up after engine is at operating temp.
Paul Shovestul
do you know a link that talks about the ignition coils, or a little more info about the "ringer" test? or a link to that thread? thanks
-karl
how can i test the injectors to see if there at fault i don't wnata waist a nother dme. and can i buy repplacement parts for the dme
at 200 bucks a pop its not a very cheap diagnostic
Bellicose Right Winger
07-08-2005, 04:09 PM
$200 for a coil or a DME?
Which is why I suggest openning the yellow pages, find list of television repair shops, make a few phone calls to find someone with a coil tester, a flyback tester or ringer and ask them how much to test 6 coils.
I just tried to ring a couple of working fuel injectors and they don't ring so you'll have to rely on resistance test for them.
What corner of the country/world are you in?
Paul Shovestul
at 200 bucks a pop its not a very cheap diagnostic
We had a tv repair shop test the ignition coils... Whats the likely hood of everyone being bad. he said 5 rings each what ever that means.
Yah i took them to a tv repair shop right when u said that and i told him which two pins were the primary and he said that all of them tested the same and thats bad. 200 a pop is the ecu. USA california
Bellicose Right Winger
07-08-2005, 05:32 PM
Good job. Sounds like he uses the same ringer I use. 5 rings is bad for a flyback, but may not be bad for an ignition coil. The number of rings isn't as important as the number of rings being the same for all coils. Seems to me I was only getting 4-5 rings when I tested my M50 coils a few months back. My car runs fine, but I wanted a baseline in case I suspect coil in future.
How much did the shop charge you? I notice that you don't fry the DME until engine runs for 30 minutes. By then engine and coils are good and warm. Is the shop close enough that you can heat the coils to 200F in an oven and take them over for a hot test?
Paul Shovestul
Yah i took them to a tv repair shop right when u said that and i told him which two pins were the primary and he said that all of them tested the same and thats bad. 200 a pop is the ecu. USA california
yah its close and he did it for free.
Javier
07-09-2005, 11:06 AM
Ignition vs injection.
Javier
Ok well i guess the coils are good since i got 5 rings out of them. So that leaves me with injectors. I don't realy understand how they work but when i hook a volt tester to the two pins that go into them i have +12vdc when the key is in posisition 2 regurdless if the ecu is hooked up or not. Again my test could be flawd but im not shure as how the fuel injector system works thus how do i test it for faults? i tested the wires and they all make contact and none of them go to ground. so a little help here is needed to test. thanks
-karl
Where can i get the dme tested? and is there any like "hardcore" reset for it thats more than just briging the two leads to the bat. together? (while unhooked ofcorse) and again
"The DMEs are in-fact fried. No, we didn't test them on other vehicles, but anytime we plug a new ECU in, it works. (For how long.. nobody knows)
I DO think it's either coils, injectors or wiring SOMEWHERE, but I don't think it has to do with wire movement as this last ECU died while we were at a stop. It's frustrating."
Javier
07-09-2005, 01:06 PM
may be a wrong test set up, the injectors are powered from the battery (straight, no fuses) trough the DME relay, when you turn on key, they are feed 12 Vdc at one of their pins, the other pin go to the DME, which will connect to ground only for short periods, properly synchronized, in order to "inject" fuel on time, if this second pin is permanently grounded, the injector is permanently opened and as long as there is fuel pump pressure, you will have a stream of fuel going into the intake manifold.
You said you have 12 Vdc measured with a meter, but as the wire to the DME is a high impedance this measure may be wrong. wire a small bulb in parallel to the injector, if the bulb light up, permanently, with the DME unhooked, you have a short to ground in the wire from the injector to the ECU, or inside the injector. Unplug the injector and repeat the bulb test in the connector to discard shorted injector.
Javier
one thing i thought of maby im serarcing in all of the wrong places what if my voltage regulator is fryd and its overvolting the dme? theres no way to test that because i cant get the car to run but it may be a possiblility
Javier
07-09-2005, 01:30 PM
shorted ones and not a damaged DME. You have not tried the presumably fried DME in other cars!!!
Javier
Javier
07-09-2005, 03:47 PM
an issue with injectors, in fact, you did not fried the loan unit because you were running also borrowed injectors.
You may have a short, in one of them, that is developed only after it gets hot, check your ecu, specially in the printed circuit paths coming from the injector output pins (3, 4, 5, 31, 32, 33). Being the injectors circuit not fused, you will probably find path damage, as nothing stopped the current until something burned out. The faulty injector shouldn't be getting energized at all now, probably due to open circuit damage at ECU, but consider that being the injectors operated by the same IC, the rest of them may be permanently energized now.
This is an Hypothesis, as you may guess, some facts would confirm it, heavy flooding on all cylinders but one, ground continuity in all injector wires (with ecu connected) but one.
If so is the case, new injector and a ecu repair will do, note from the ecu drawings that the IC responsible for injector handling is S470.1, you have some other IC's the same type in the ECU, so a good electronic technician may be able to use one ecu to fix the other. Hopefully, this IC damage didn't produce extra damage to other components.
Javier
Ok you pointed out a real big point and im going to check that tormow after the bmw drive training thing. i opend up the dme and it smells sort of smoaked out and i briefly examand the traces. im going to test resistance between each pin and then the lead on the injector chip. how can i tell if the chip is fry'd? or if its something elts and also can i buy another one of the injector chips? oh and the injector chips on my ecu is actuly 2 of em. one does 1 3 2 and other does 4 6 5
no you were right all one chip. so i should test my dme in another car and see if same problem presists? and if it does then dme = dead. after that what do i test?
Javier
07-10-2005, 07:13 AM
it is a market standard chip. If I was to design this output, I would probably use opto-coupling devices for the driving outputs, in order to protect inner electronics from an overvoltage/overcurrent situation. So hopefully, nothing else is damaged and you can write down the part number from the IC and look for it on an electronic component store. You are close to Silicon Valley, there should be plenty of silicon over there, not referring to fake boobs je je! Also remember you have 3 chips on each DME, but careful, a bad removal operation can ruin any chip.
An immediate indication that the chip is fried would be a low resistance measure to ground (leads 5, and 6 of the chip) from leads 7 to 12 of the chip. You can double check comparing these readings with any other identical chip in the board.
Also verify, as you said, continuity from the Chip Leads to the Box output Pins, use this table: CL7 to BP33, CL8 to BP5, CL9 to BP32, CL10 to BP4, CL11 to BP31, CL12 to BP3. Inspect this paths in the board, shouldn't be overheated, if they look weird in any form, reinforce/replace the connection with an insulated wire (Wire-wrapping wire is OK for this). If you find an overheated path, take good care of identifying the corresponding injector. The wire from the DME to the injector, or the injector itself (must probable), is the one that is frying the DME. Note that whatever is the damage, we are not talking grounding of the line, but shortcircuiting (connecting) to 12 Vdc. That is the reason I believe the two wires to the injector are being shortcircuited, or there is an internal damage in the injector, shortcircuiting totally or partially the injector coil.
Of course, this all presumes the problem is in the injectors system. We are not positive yet, isn't it?
Javier
Bellicose Right Winger
07-10-2005, 07:17 AM
Need to be careful with these coil test results as we're in uncharted territory here. If coils were easy to test someone would likely have come up with a procedure by now. The ringer only tests for shorted turns in the coil. It doesn't test for high voltage breakdown and it doesn't test at operating temperature. It's possible coils only short at operating temp and when making 35kv sparks. It's also conceivable that coil failure puts 35kv spike into the DME, which would ruin all sorts of semiconductors inside.
New coils are $55 ea at Zygmunt.
If you measure 12 volts at both FI terminals when connector is on FI that's normal. It won't matter whether or not DME is hooked up. You're using a high impedence DMM, which draws very little current, so voltage drop thru FI coil is negligible and you read 12 volts on the DME side of FI.
You should repeat this test with all FI's disconnected from the harness. In this case you should only measure 12 volts at one of the FI connector terminals. Do this with and without DME connected. If you measure 12 volts at both terminals with DME disconnected, then I think you've got a wiring problem. If you measure 12volts at both terminals with DME connected, then I think you've got a bad DME.
Is it possible to remove a coil, lay it on its side, reconnect coil connector, put spark plug in connector, ground spark plug and crank engine to check for spark? This will tell us whether problem is fuel, ignition or both.
Best DME test is to plug it in to a working 525i.
Paul Shovestul
Ok well i guess the coils are good since i got 5 rings out of them. So that leaves me with injectors. I don't realy understand how they work but when i hook a volt tester to the two pins that go into them i have +12vdc when the key is in posisition 2 regurdless if the ecu is hooked up or not. Again my test could be flawd but im not shure as how the fuel injector system works thus how do i test it for faults? i tested the wires and they all make contact and none of them go to ground. so a little help here is needed to test. thanks
-karl
Where can i get the dme tested? and is there any like "hardcore" reset for it thats more than just briging the two leads to the bat. together? (while unhooked ofcorse) and again
alright ima start checking. one last question before i start if i cant figure this out do you guys think a shop might be able to and if so what should I tell them?
ok i have the dme appart and am testing it:
Ok Sofar no traces are gone and im moving onto the step of testing the chip
Ok tested the resistance of the chip and its all around 33.04k ohms-33.30k ohms... should i test the chip thats next to it and it runs the fuel pump relay check engine light and the evap purg and the o2 sensor... i found some weard trace damage in 2 places and am unshure to the cause because this is a used ecu and did work when i first put it im... I'm gonna take pictures
EDIT:
I have dme with bosh part number 0 261 200 402 would that be why it died because the orignal one had a green sticker on it... i noticed that because the schmatic was a little diferent than the actul board. i don't have 3 of the s470's on this board
Javier
07-11-2005, 02:41 PM
related to the trace damage.
Follow the box pins from the other two output chips (1, 8, 36, 37, 2, 29, 48) to see what are the output chips for them, in any case, doesn't matter if you identified and located the injector circuits. Also check the second DEM damaged in your car to verify similarities in the readings and the race damage.
Javier
Edit:
33 k seem OK, enough impedance as to be considered an open circuit (I mean, injectors will not turn on connected trough this resistance). If 33K is the read value from each of box pins 3, 4, 5, 31, 32, 33 to ground (Box pin 6), then you have no shortcircuited outputs.
May be the issue is not injector related.
my mind is boggled i calld a shop and they said they would give it a look and try to fix it for 90$ so im gonna give that a try but ill keep you guys updated.
Its not injector related i checked everything i checked for path's to ground and everything is their a possibility that this is connceted to the trans program error? mabe the trans computer is dead and its causeing the ecu to take a poop? im not shure hopefully the guys at the shop can point me in the right direction but ill keep you guys updated.
Sofar they plugged it into their computer and said that the dme told them that it was a supply power problem or something of the like the guy was brief and I didn't get a chance to ask much more but he did mention that he switched the ecu for a working one and put a new relay on it and still has problem. Im starting to think that their not going to find the problem and if so im not shure where to go from here.
Well just thought id keep you guys updated,
-karl
PS
I need a repplacement ECU for my car now I posted in the Classifieds
Javier
07-15-2005, 02:09 PM
Javier
Also check the resistance of each pin of the injector to ground -- should be no continuity to ground. That's the short that will fry an ECU
haha my names karl and its spelt with a k now i know why i couln't make that one hehe
well i talked to the guys and there pirtty shure a new engine wireing harnis would solve the problem. where and how much are these things?
Heres another post related to the stupid m50 not starting what do you guys think? http://www.bimmer.info/forum/showthread.php?t=12424
Hey!! I'm getting my ecu today and need some real quick help!!!! When i go to test to see if iv figured out the problem today is it possible to fuse the dme so that it won't die or reduce the risk of killing it. then when im done i can bypass the fuse i jsut want to not kill this dme.
bump. don't wnata kill another ecu
FIGURED IT OUT took apart the wireing harnis and there were a few melted wires that melted together so im going to try and splice the wires back together and shrinkwrap them together but i need a wireing diagram of the engine compartment w/ colors i don't kno where to find them.
Alright well i figured out that one green wire w/ /// stripe got short circuted and turnd red hot melting off the coating on it. Also that fused one or two other wires to it. Since it goes into a rubber boot under the intake manifold how should i go about repplaceing if its inside a rubber boot? should i cut the boot w/ a razor blade very carefully and then just tape it up like crazy with E-Tape?
So please help me out on this one im SOOOO close to fixing this beast and thanks for all of your help sofar.
Ok,
Sorry for the overload of posts!! im just very excited after a month of trying to figure this out we finely got it. I traced the wire down and it goes to the relay inside the ebox closest to the fender. and then it goes from there under the intake manifold inside that rubber conduit. So I need a few tips on how to diagnosis this problem.
EDIT:
i don't wnata post again but here is the problem... the oxygen sensor was faulty causing the wire to burn up i traced it all the way under the car to the oxygen sensor... all of the wires are melted at that point.
Actuly it was the oxygen sensor heater that was causing the problem... so at this point should i just make shrue the ecu wires are all good to go EX. not touching anything elts and should i repplace the oxygen sensor and re run the wires?
Unless anyone has any last ditch briliant ideas I think the cars going to get donated or something... i don't kno what elts to do i brought it to a shop and they couln't figure it out
Javier
07-23-2005, 07:23 AM
culprit. Fix every thing you found out of place.
If the wire carrying 12 Vdc to the O2 sensor is fried (Green/Blue wire), and the copper can touch the copper on surrounding wires, it is enough that this second wire pertains to an output driver to fry it, and the ECU will remain unusable. Also, a short in this wire will drop down the voltage disturbing ignition coils, injectors, and fuel pump relay. Do not give up, that for sure won't fix the car.
I would suggest to make an exhaustive inspection of the engine harness, look for damage everywhere, specially what is related to the ECU. Fix any insulation damage you find, and try again.
Did you ever learn what was fried in the ECU? This info would help a lot on determining where to look.
Javier
PS: Check your mail.
Hey whats up guys. Im getting the engine wiring harness today!!! its complete from the ecu connector to every sensor and the coilpacks and injectors. I was wondering if any of you guys have attempted such a project as replacing the engine wiring harness and im wondering how hard you guys think it may be or any advice on the best way to do it. i already removed the intake manifold and i am leaving the old harness in so that i can see where all of the connectors go.
uscharalph
08-12-2005, 01:05 PM
Hey whats up guys. Im getting the engine wiring harness today!!! its complete from the ecu connector to every sensor and the coilpacks and injectors. I was wondering if any of you guys have attempted such a project as replacing the engine wiring harness and im wondering how hard you guys think it may be or any advice on the best way to do it. i already removed the intake manifold and i am leaving the old harness in so that i can see where all of the connectors go.
Wow! That seems like a pretty big project.
i don't think its going to be that hard as i already have the intake manifold off and all i have to do is pull the wires out from under that. and isn't the only other part going to be routing wire to dme
and then to the round plug that connects the loom to the obd?
upallnight
12-15-2007, 04:33 AM
So what happen?
Did you ever fix your car?
Were you able to replace the engine harness?
89_525i_PhoenixAZ
02-28-2008, 12:05 AM
inquiring minds want to know!!!
Hypr5
03-21-2008, 11:44 AM
Wow this thread is old. This was 3 years ago, I think.
Anyway, the new wiring harness did fix the car and it ran well until he sold the car :)
Powered by vBulletin® Version 4.2.3 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.